This proposal is part of the Collaborative Studies of the Psychobiology of the Depressive Illnesses, which are under the aegis of the Clinical Research Branch of the Division of Extramural Research Program of the NIMH. The purpose of the Collaborative Studies is to clarify the nosology of the depressive illnesses, examine the role of genetic factors in the development of depression, and explore the relationship between clinical, biological, and psychophysiological variables. The present protocol is for a pilot and feasibility study of the larger Collaborative Studies of the Psychobiology of the Depressive Illnesses. Two hundred patients with affective disturbance will be evaluated at the five participating facilities using the battery of initial assessment procedures that will be used in the larger study. Data from this study will be analyzed in terms of the hypotheses of the larger study, the relationship between the assessment of instruments, and the interjudge reliabilities of the clinical procedures. Work will be done on the development of a new instrument (the Inventory of Discrete Events, the IDES) specifically designed to record the occurrence of life events prior to the onset of an episode of psychopathology, to evaluate several alternative forms of this instrument and to arrive at a final version whose reliability will be tested within the framework of the Collaborative Study. Several aspects of the association between life events and affective illness will be explored in some detail with a view to developing an instrument that will not only record the occurrence of an event but will also provide information about some of its characteristics and pecularities. Specific hypotheses for further investigation within the framework of the Collaborative Study will be developed.